U.S. patent application number 11/363139 was filed with the patent office on 2007-08-30 for tubular filter material assemblies and methods.
Invention is credited to Patrick McGrenera, Ruediger Tueshaus.
Application Number | 20070199889 11/363139 |
Document ID | / |
Family ID | 38442996 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070199889 |
Kind Code |
A1 |
Tueshaus; Ruediger ; et
al. |
August 30, 2007 |
Tubular filter material assemblies and methods
Abstract
A continuously or intermittently bonded spirally wrapped tubular
filter material screen comprises one or more strips of filter
material. The spirally wrapped tubular filter material screen may
or may not comprise multiple layers of filter material. In one
embodiment, strips of wire mesh are resistance welded to comprise
one or more helical resistance welds. The spirally wrapped tubular
screen can be cut to any desired length.
Inventors: |
Tueshaus; Ruediger;
(Dorsten, DE) ; McGrenera; Patrick; (The
Woodlands, TX) |
Correspondence
Address: |
KENNETH L. NASH
P.O. BOX 680106
HOUSTON
TX
77268-0106
US
|
Family ID: |
38442996 |
Appl. No.: |
11/363139 |
Filed: |
February 27, 2006 |
Current U.S.
Class: |
210/497.01 ;
166/230; 166/231; 210/499 |
Current CPC
Class: |
B01D 29/111 20130101;
B01D 29/21 20130101 |
Class at
Publication: |
210/497.01 ;
166/230; 166/231; 210/499 |
International
Class: |
B01D 29/00 20060101
B01D029/00 |
Claims
1. A tubular screen, comprising: a woven metallic screen comprising
one or more woven mesh strips secured together with at least one
continuous spiral electro-resistance weld, said woven metallic
screen being constructed without adding any or any substantial
amount of metal particles thereto prior to being welded with at
least one continuous spiral electro-resistance weld, said woven
metallic screen comprising spiral seams between said one or more
woven mesh strips.
2. The tubular screen of claim 1 further comprising a plurality of
layers of woven mesh strips.
3. The tubular screen of claim 1 being self supporting to receive
screen inspection tools into an interior of said tubular screen
whereby said tubular screen can be quality checked.
4. The tubular screen of claim 1 wherein said tubular screen has a
length greater than ten feet.
5. The tubular screen of claim 1 further comprising a plurality of
continuous spiral electro-resistance welds, said plurality of
continuous spiral electro-resistance welds being parallel with
respect to each other.
6. The tubular screen of claim 1 wherein said screen is at least
five feet long and is formed by cutting off said tubular screen
from a longer tubular screen.
7. A tubular filtering screen, comprising: an innermost surface for
said tubular filtering screen comprising one or more spirally
wrapped strips of filter material, said one or more spirally
wrapped strips of filter material comprising a continuous bond
securing said one or more spirally wrapped strips of filter
material together along a spiral bonding path, said innermost
surface being open to an interior of said tubular filtering screen
such that an inspection light can be inserted into said interior
and utilized for checking a quality of said tubular filtering
screen.
8. The tubular filtering screen of claim 7, wherein said one or
more spirally wrapped strips of filter material comprise one or
more woven wire strips continuously bonded together by being welded
together along at least one continuous spiral welding seam.
9. The tubular filtering screen of claim 8, further comprising a
plurality of continuous spiral welding seams.
10. The tubular filtering screen of claim 8 being constructed
without adding any or any substantial amount of metal particles to
said one or more woven wire strips prior to being welded together
along said at least one continuous spiral welding seam.
11. The tubular filtering screen of claim 10 wherein said at least
one continuous spiral welding seam comprises at least one
continuous spiral electro-resistance weld.
12. The tubular filtering screen of claim 7, wherein a length of
said tubular filtering screen is greater than about ten feet.
13. The tubular filtering screen of claim 7, wherein said tubular
filtering screen is adapted for positioning without at least one
outer tubular positioned around said tubular filtering screen or at
least one inner tubular positioned inside said tubular filtering
screen.
14. The tubular filtering screen of claim 7 wherein said tubular
filtering screen is at least five feet long and is formed by
cutting off said tubular screen from a longer tubular screen.
15. A tubular filtering screen, comprising: a spirally wrapped
woven wire screen, said spirally wrapped woven wire screen
comprising one or more woven wire strips being spirally wrapped and
bonded together along a spiral bonding path, said screen being at
least five feet long and being formed by cutting off said tubular
screen from a longer tubular screen.
16. The tubular filtering screen of claim 15 wherein said one or
more woven wire strips are continuously bonded together by being
welded together along at least one continuous spiral welding
seam.
17. The tubular filtering screen of claim 16 being constructed
without adding any or any substantial amount of metal particles to
said one or more woven wire strips prior to being welded together
along said at least one continuous spiral welding seam.
18. The tubular screen of claim 15 wherein said tubular screen has
a length greater than ten feet.
19. A method for making a tubular screen, comprising: continuously
spirally wrapping a woven mesh screen to form said tubular screen;
welding said spirally wrapped woven screen; and cutting said
tubular screen to a desired length.
20. The method of claim 19, further comprising continuously welding
said spirally wrapped woven screen.
21. A method of making a tubular filtering screen, comprising:
securing one or more woven metallic strips together with at least
one continuous spiral electro-resistance weld, said one or more
woven metallic strips being initially secured together so as to be
free standing such that a light is receivable through an interior
of said filter material screen to measure a quality of said tubular
filtering screen; and subsequently securing said filter material
screen within an outer tubular.
22. The method of claim 22, further comprising forming end caps on
said outer tubular.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to tubular filter
material assemblies and, more particularly, to apparatus and
methods for continuously or intermittently bonded spiral wound
tubular filter material assemblies and/or machines for making
tubular filter material assemblies.
[0003] 2. Description of the Background
[0004] Tubular filtering screens may comprise steel, plastic, or
other filter materials. For instance, tubular filter material
screens comprised of wire mesh filter material may be used in oil
field well bores for downhole sand control. When used downhole for
sand control purposes, the tubular screen might be part of a gravel
packing construction around the well bore in a pay zone of interest
to limit the flow of sand into the wellbore, and thereby extend
time of operation of the well.
[0005] When welding tubular filter screen material together, TiG
and MiG welding may damage wire mesh and produce holes in the sand
control tubular screen which permit leakage through the screen.
Resistance welding has not been particularly useful for tubular
screens of any significant length because of the need for an
interior electrode.
[0006] In some cases, tubular screens are manufactured by wrapping
filter material around a perforated body. However, these tubular
screens are problematic in that the screens cannot be inspected
using techniques such as passing a light through the center of the
screen. Therefore, the quality is dubious. As noted above, filter
material is very difficult to weld. In some types of filter
material, a hole can be formed with the flame from a cigarette
lighter. Welds that cannot be checked are problematic due to the
possibility of leaks after incurring the high costs of placing such
screens downhole. Thus, in many cases, tubular screens formed by
wrapping filter material around a support tubular such that the
screens are permanently secured to the support tubular are not
acceptable due to the inability to make quality checks of the
filter material screens using techniques such as passing a light
through the center of the screen. As well, this type of
construction is not flexible for logistical purposes. It may often
be desirable that the tubular screen and the pipe be separately
made and assembled at another desired location to offset the
transportation cost logistics.
[0007] Screens may also be made with woven screens dipped or
covered with sintered metal particulates which are then spirally
wrapped around support tubulars and welded, but this construction
is expensive and the support tubulars again prevent the possibility
of quality checks that utilize a light passing though the interior
of the screen to verify the absence of holes produced by
welding.
[0008] While tubular or cylindrical mesh screens which are not
built on perforated forms are well known, these prior art tubular
filter material screens are time consuming to build and quite
expensive. These tubular filter material screens are formed in
sheets having a selected but limited length. The sheets are rolled
to form a tubular of the selected length, and then welded along the
longitudinal seam. The tubular screen can then be inspected such as
by passing a light through the center of the screen to check for
imperfections. However, the straight lengthwise weld of the filter
material requires significant expertise to make and is time
consuming and costly, even if the weld is made by machine. It will
also be understood that this assembly first requires obtaining one
or more sheets of filter material having the desired dimensions for
the cylindrical screen to be created. Because the sheets of mesh
screens may be limited in size, and due to the difficulties of
welding along the length of the screens, in many cases several
cylindrical mesh tubes must be welded to end caps which are then
secured together to form a cylindrical screen of the desired
length.
[0009] The above cited art provides filter screens that have
significant cost problems, quality problems and/or logistics
problems. Consequently, there remains a long felt need for improved
methods for more quickly making such screens at lower costs. Those
skilled in the art have long sought and will appreciate the present
invention which addresses these and other problems.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide an
improved tubular screen and a machine for making the improved
tubular screen.
[0011] It is yet another object of the present invention to provide
a tubular screen that may be made in a continuous or endless
process such that the tubular screen can be simply cut off at any
desired length.
[0012] It is yet another object of the present invention to provide
means for quickly and continuously bonding spiral wrapped
cylindrical screens of any length.
[0013] It is yet another object of the present invention to provide
a means for forming the screen in a continuous manner so that it is
initially self-supporting without the need to permanently form and
weld the tubular mesh screen on a metallic support tubular so that
an interior inspection may be made to verify weld quality.
[0014] These and other objects, features, and advantages of the
present invention will become apparent from the drawings, the
descriptions given herein, and the appended claims. However, it
will be understood that the above-listed objectives and/or
advantages of the invention are intended only as an aid in quickly
understanding aspects of the invention, are not intended to limit
the invention in any way, and therefore do not form a comprehensive
or restrictive list of objectives, and/or features, and/or
advantages.
[0015] Accordingly, one embodiment of the present invention
comprises a tubular screen which may comprise one or more elements
such as a woven metallic screen or other filter material screen
which may comprise a plurality of woven mesh strips or other strips
of filter material secured together with at least one spiral
electro-resistance weld or other types of bonds. When using
metallic mesh as the filtering material, the tubular screen may in
one possible embodiment be constructed without adding any or any
substantial amount of metal particles to the screen prior to being
welded together. The plurality of filter material strips may be
welded together with at least one continuous spiral
electro-resistance weld. The screen may comprise continuous or non
continuous spiral seams or other types of seams. If used, a spiral
electro-resistance weld may be coincident, parallel, or
substantially parallel to the spiral seams between the plurality of
filter material strips. The tubular screen may further comprise a
plurality of continuous spiral electro-resistance welds which may
be parallel with respect to each other.
[0016] The tubular screen may comprise a plurality of layers of
woven mesh strips and/or other types or layers of filter material.
The continuous tubular screen may be any length and may be a long
length, such as a length greater than ten feet. In one embodiment,
the tubular screen is at least five feet long and is formed by
cutting off the tubular screen from a longer tubular screen.
[0017] The tubular screen may be self supporting so as to comprise
one or more of the plurality of woven mesh strips along the inner
surface thereof and avoid the need for a support tubular. For
instance in one possible, instead of a support tubular, the tubular
filtering screen may comprise an innermost surface which itself is
a spirally wrapped woven wire screen comprising a plurality of
woven wire strips that may be continuously bonded together along a
spiral bonding path. The tubular filter may comprise an interior
open for use of an inspection light which can be shined through the
tubular filter to check for defects.
[0018] The present invention may further comprise a machine capable
of making tubular filters such as, for example only, a spiral
wrapped wire mesh tubular screen from one or more strips of wire
mesh. The machine may comprise a mandrel with an outer surface and
may also comprise a strip feed to deliver one or more wire mesh
strips onto the outer surface of the mandrel. One or more wire mesh
strips may be directed onto at least a portion of the outer surface
of the mandrel for forming a shape of a wire mesh tubular screen.
An exterior welding electrode may be positioned outside the
exterior wire mesh surface and an interior welding electrode may be
positioned along the interior wire mesh surface of the one or more
wire mesh strips. In this example, the interior welding electrode
could cooperate with the exterior welding electrode for welding the
one or more wire strips together.
[0019] In one possible embodiment, the mandrel may further comprise
a tubular and at least a portion of the interior welding electrode
may be positioned within an interior of the tubular. The mandrel
may further comprise a mandrel opening in the outer surface of the
mandrel and an interior welding electrode may be positioned within
the opening. In this embodiment, the opening might possibly
comprise a curved slot. The interior welding electrode may comprise
at least one inner welding wheel. The inner welding wheel may or
may not be driven to thereby spirally move or assist in moving the
one or more wire mesh strips around the outer surface of the
mandrel as the one or more wire mesh strips are continuously
spirally welded together. In one possible embodiment, the outer
welding electrode might comprise at least one outer welding wheel
and may comprise one or more electrically insulated disks.
[0020] The machine may further comprise a filter material strip
drive which frictionally engages the one or more wire mesh strips
to spirally wrap the one or more filter material strips around the
mandrel and past an outer bonding element and an inner bonding
element such that the one or more filter material strips are
continuously or non continuously bonded together spirally or in
other patterns or random patterns. The machine may also comprise at
least one feed for at least one strip of paper or other materials
as desired. The machine may comprise means for continuously
spirally wrapping a plurality of filter material strips around a
mandrel.
[0021] A method is provided for making a spiral wrapped tubular
screen from one or more strips of filter material which may
comprise continuously spirally forming a tubular with the one or
more strips. Other steps may comprise continuously spirally bonding
the one or more strips such that a spirally bonded length of the
spirally wrapped tubular screen moves continuously axially. The
method may further comprise continuing to produce the spirally
wrapped tubular screen until a desired length is reached.
[0022] Another method for making a tubular screen of a desired
length may comprise spirally wrapping a woven mesh screen to form
the tubular screen, continuously welding the spirally wrapped woven
screen; and cutting the tubular screen to the desired length. The
filter material may comprise woven filter material, plastic
material, woven plastic material, metal fiber, extruded mesh,
sintered, extruded mesh, or other desired filter materials.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is an elevational view, in section, showing an inner
welding wheel supported at a first angle with respect to a tubular
screen and mandrel in accord with one possible embodiment of the
present invention;
[0024] FIG. 2 is a plan view in section showing the inner welding
wheel supported at an angle related to the angle of the helical
seam of the filter material ribbons to be welded together which is
a function of the mandrel diameter and width of filter material
ribbons to be welded together in accord with one possible
embodiment of the present invention;
[0025] FIG. 3 is a plan schematic view, with internal wheel shown,
of a tubular filter material construction machine with filter
material and which may also utilize paper strips or other friction
reducing material being continuously fed onto a mandrel and rotated
around the mandrel for welding together to form an endless cylinder
in accord with one possible embodiment of the present
invention;
[0026] FIG. 4 is an elevational view, partially in section, of
relevant portions of a tubular filter material construction machine
comprising dual outer welding wheels, a single inner welding wheel,
a mandrel, and a support stand in accord with one possible
embodiment of the present invention;
[0027] FIG. 5 is an elevational view of a frame supporting a
mandrel and outer welding wheel viewed along lines 5-5 of FIG. 4 in
accord with one possible embodiment of the present invention;
[0028] FIG. 6 is a plan view looking down on the machine of FIG. 4
wherein details of the dual outer welding wheels and support
therefore may be seen in accord with one possible embodiment of the
present invention:
[0029] FIG. 7 is a perspective simplified view of a tubular filter
material construction machine showing a configuration for an outer
welding wheel, inner welding wheel, and tubular mandrel in accord
with one possible embodiment of the present invention;
[0030] FIG. 8 is an elevational view of a spiral wrapped
continuously bonded tubular filter material screen that may be of
any length and may be freestanding without the need for an inner
support tubular in accord with the present invention; and
[0031] FIG. 9 is an elevational view in section of a spiral wrapped
continuously bonded tubular filter material screen positioned
within an outer tubular in accord with the present invention.
[0032] While the present invention will be described in connection
with presently preferred embodiments, it will be understood that it
is not intended to limit the invention to those embodiments. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents included within the spirit of the invention and as
defined in the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Referring now to the figures, and more particularly to FIG.
7, there is shown an overview of presently preferred basic
components of machine 10 for making a filter material cylindrical
screen in accord with one possible embodiment of the present
invention. The machine is operable to make endless spiral wrapped
continuously bonded tubular filter material screens which may or
may not comprise multiple layers of filter material and, in this
embodiment, are continuously resistance welded along the helical
seams of filter material strips comprising woven wire which are
utilized within this particular tubular screen.
[0034] In a presently preferred embodiment, the welding electrodes
may, if desired, be designed as wheels such as outer welding roller
or wheel 12. However, the invention is not limited to use of
welding wheels and could use any type of welding electrodes or
bonding devices.
[0035] As shown in FIG. 7, outer welding wheel 12 is positioned
over slot 14 on mandrel 16. As used herein, a mandrel is a tool
used as a form or to form a work or in this case a filter material
tubular. Outer welding wheel 12 cooperates with inner welding
roller or wheel 18 (which may be seen for instance in FIG. 1).
Inner welding wheel 18 is positioned in slot 14 opposite outer
welding wheel 12 for welding ribbons or strips of woven filter
material. As discussed subsequently in connection with FIG. 3,
ribbons or strips of woven filter material, such as ribbons 26 and
28, comprise at least one filter material strip feed to direct the
filter material strips or ribbons onto mandrel 16 whereupon they
are spirally driven around mandrel 16 between outer welding wheel
12 and inner welding wheel 18 and are thereby spirally welded
together at or adjacent the seams thereof.
[0036] Utilizing resistance welding in accord with one embodiment
of the present invention helps mitigate damage to the filter
material screens during the welding process. Also in accord with
embodiments of the present invention, the weld may form one or more
continuous helical weld beads or lines which secure the ribbons or
strips of filter material together. The ribbons or mesh to be
welded may be abutting or overlapped by a selected amount as
desired. One or more corresponding welded seams are formed which
permanently secure the ribbons together.
[0037] Outer shaft 20 rotatably supports outer welding wheel 12.
Inner shaft 22 rotatably supports inner welding wheel 18. Outer
shaft 20 and/or inner shaft 22 may or may not be driven to thereby
assist in moving filter material strips around mandrel 16. Many
variations of outer shaft 20 and inner shaft 22 are possible some
of which are shown herein. For instance, inner shaft 22 may or may
not extend through the side of mandrel 16. However, in the
embodiment shown in FIG. 7, inner shaft 22 extends through opening
24 in mandrel 16. Outer shaft 20 and inner shaft 22 may or may not
be parallel or aligned.
[0038] For resistance welding, electric current flows between outer
welding wheel 12 and inner welding wheel 16 through slot 14 and may
flow in different current paths and/or directions and/or through
the ribbons more than once, as discussed below.
[0039] Slot 14 in mandrel 16 may preferably be curved. A curved
design for slot 14 provides several advantages. One advantage is
that the space between the edges of slot 14 and the outer edges of
the welding wheels can thereby be kept as small as possible so that
mandrel 16 provides good support for the portion of the filter
material strips to be welded by outer welding wheel 12 and inner
welding wheel 18.
[0040] As well, it will be appreciated that adjustments in the
angle of welding may also be desirable and accommodated by the
curve in slot 14. The coiling-angle .alpha. is a function of
mandrel 16 diameter D and filter material ribbon width B so that
.alpha. may be equal to or proportional to sin B/(D*.pi.).
[0041] The coiling-angle is the angle of the helix or seam of the
mesh ribbons to be welded together with respect to the centreline
of the coil. As noted in FIG. 3, the filter material strips may
preferably be fed onto mandrel 16 as close as possible to the
desired coiling angle. The ribbon width B may effectively vary
depending not only on the actual width of the ribbon strips or
filter material but also whether the seams are abutting or
overlapping and/or the amount of overlap. The effective diameter D
of mandrel 16 depends on the diameter of mandrel 16 but may also
effectively vary due to the number of layers of filter material and
the thickness of each filter material layer.
[0042] The present invention is not limited to any particular
mechanical construction for alignment and/or adjustment of inner
wheel 16 and outer wheel 12 with respect to the coiling angle
because many possible constructions may be utilized in accord with
the present invention depending on the desired filter material
cylinder to be produced. For instance, the relative positions of
outer wheel 12 and/or inner wheel 16 may or may not be fixed,
movable, and/or controlled or adjustable manually or under computer
control as desired and depending on the desired flexibility of
operation for machine 16 with respect to different types of filter
material cylinders to be produced. Depending on the desired
flexibility of operation, machine 10 may be designed for welding
filter material strips of a particular width and seam abutment
and/or seam overlap or may be designed to permit variations thereof
as desired. As well, depending on the desired flexibility of
operation and the subsequent complexity of machine 10, other
variations for positioning of inner wheel 16 and outer wheel 12 are
available. For instance, inner wheel 16 may be variable only in a
direction radially outwardly and inwardly and/or there may be
slight differences in the angular alignment of inner wheel 16
and/or outer wheel 12 and/or the coiling angle. Such variations may
also change depending on the type of filter material involved. For
instance, the alignment requirements for woven mesh formed of round
wires may be different than the alignment requirements for woven
mesh formed of flat wires. It will also be understood that machine
10 may allow for replacement of mandrel 16 with different diameter
mandrels and/or may provide for a variable diameter mandrel, e.g.,
mandrel 16 may be built with linear strips or segments adjustably
mounted (not shown) so that the effective diameter thereof may be
expanded or contracted radially outwardly or inwardly to produce
different diameter filter material tubulars.
[0043] FIG. 3 is a plan schematic view which shows the general
layout for tubular filter material construction machine 10A. In
this embodiment, filter material strips 26 and 28 and paper strip
30 are being continuously fed onto mandrel 16 and rotated around
the mandrel 16 for welding together to form an endless spirally
wrapped filter material cylinder 32 in accord with one possible
embodiment of the present invention. Endless spirally wrapped
filter material 32 moves in the direction of arrow 46 over and past
mandrel 16. Accordingly, the so-created filter material tubular can
be conveniently cut to any desired length. Additional ribbons of
filter material may also be utilized so that the present design is
not limited to two filter material ribbons and may utilize any
desired number of strips. For instance, as one possibility, three
filter material strips and one paper ribbon might be wound around
mandrel 16 at an angle of 14.5.degree. (not shown).
[0044] Belt 34 and pulleys 36 and 38 wrap around filter material
cylinder 32 and frictionally engage filter material cylinder 32 for
rotating it around mandrel 16. Belt 34 may be angled as desired and
in this embodiment is slightly offset with respect to the angle of
welded seam 50. For instance, in this embodiment, angle 48 of
engagement of endless belt 34 with filter material cylinder 32 is
approximately 58 degrees whereas angle 52 of welded seam 50 is
somewhat less at 45 degrees. As noted above, outer welding wheel 12
and/or inner welding wheel 18 may be used with and/or replace other
types of drives. Other types of drives such as rubber wheels,
belts, built-in drive sections on mandrel 16, internal wheels with
additional slots in mandrel 16, or the like may also be used as
desired for rotating filter material cylinder 32 around mandrel
16.
[0045] Insulative or friction reducing material strip 30, such as
paper or other suitable materials, may be used as an electrical
insulator and may also be selected to reduce the friction of
rotating the so created filter material cylinder 32 around mandrel
16. Paper strip 30 is preferably smaller in width than the widths
of filter material strips 26 and 28 to thereby provide a continuous
slot on the inner surface of the combined strips 26, 28, and 30
whereby access to filter material strips 26 and 28 is available to
inner welding wheel 18 for resistance welding purposes. Except for
the continuous slot, paper strip 30 electrically insulates filter
material cylinder 32 from mandrel 16 so that little or no
electrical current preferably passes between filter material
cylinder 32 and mandrel 16. As well, mandrel 16 could possibly be
made of electrically insulating materials or compounds rather than
metal, although metal is a relatively easily available and low-cost
material that provides a long lasting mandrel.
[0046] In the embodiment shown in FIG. 3, the interior workings of
one possible embodiment of inner welding wheel 18 are shown through
the filter material and mandrel where inner welding wheel 18 is
mounted inside the interior of mandrel 16. In this embodiment,
inner welding wheel 18 may be driven by shaft 40 and universal
joint 42 to help rotate the filter material being welded together.
Inner welding wheel 18 is supported for low friction by bearing
assembly 44 and bearing assembly 45.
[0047] In this embodiment, but not in all embodiments, electrical
power to inner welding wheel 18 may be provided via cable 54 where
it is connected to inner welding wheel shaft 56 through cylinder
58. Cable 54 could be shorted to mandrel 16 or may be connected to
a power supply as desired. In other embodiments, no cable is
needed. For instance, as discussed below for use with a double disk
outer welding wheel 12 described hereinbelow, wheel 18 provides a
shorting connection between the double disks and therefore no cable
is needed.
[0048] FIG. 1 shows inner welding wheel 18 supported internally
within mandrel 16 in accord with one possible embodiment of the
present invention. In this embodiment, welding wheel 18 is mounted
on support 62 (which may or may not extend through mandrel 16) at
an angle with respect to an interior surface of tubular screen and
mandrel 16. The angle is related to the conical angle formed on
substantially flat surface 60 of welding wheel 18. It is seen that
welding wheel 18 extends through slot 14 for engaging the interior
surface of the tubular screen. While a substantially flat surface
is shown for welding wheel 18 here, other possible surfaces such as
rounded, elliptical, multiple rounded surfaces, and the like may
also be utilized. Flat surface 60 is almost as wide as slot 14
thereby providing significant support for the filter material. If
desired, the edges of slot 14 may be angled to more closely fit to
the angle of inner welding wheel 18, i.e. the angle of the edges of
slot 14 may be the same as the angle of wheel top 72 of inner
welding wheel 18 with respect to the interior wall of mandrel
16.
[0049] In this embodiment, support 62 connects to inner welding
wheel 18 via roller bearings 64 and 66 which may also comprise
thrust bearing support. Electrical current may be applied to shaft
68 via cylinder 70 or other type of current supply connection. As
noted earlier, inner welding wheel 18 may be electrically shorted
to mandrel 16 or may be connected to electrical power as desired or
may utilize no cable at all. FIG. 2 shows welding wheel 16 looking
down from the top or in a plan view wherein slot 14 and welding
wheel 16 are aligned with the seam between the filter material
strips which is angled at 45 degrees. While a preferred embodiment
of slot 14 is curved as discussed below, it is also possible that
in some constructions, slot 14 might be straight or substantially
straight as viewed from the top as indicated here, wherein slot 14
is also shown somewhat wider.
[0050] FIG. 4 schematically shows relevant portions of tubular
filter material construction machine 10C. comprising dual outer
welding wheels 12, a single inner welding wheel 18, mandrel 16, and
support stand 74 in accord with one possible embodiment of the
present invention.
[0051] Outer welding wheel 12 may comprise wheel support and
bearing assembly or hub assembly 76 which rotates around shaft 78.
In this embodiment, outer edge 80 of outer welding wheel 12
comprises two disks 86 and 88 with outer rounded edges 82 and 84,
as perhaps better seen FIG. 6. In this embodiment, the two rounded
edges 82 and 84 engage a relatively flat or straight outer surface
of inner wheel 18 such as straight conical surface 60 shown in FIG.
1. The two relatively flat disks 86 and 88 with rounded outer
surfaces 82 and 84 may be separately bolted or otherwise secured on
hub 76. In this embodiment, flat disks 86 and 88 are electrically
insulated from each other to provide an electrical current path as
described below. Current feed to flat disks 86 and 88 may comprise
sliding, rolling, and/or spring-loaded electrical contacts as
desired.
[0052] While two rounded disks are shown in FIG. 4, more or fewer
may also be utilized. Moreover, outer welding wheel 12 may have a
flat or straight outer surface as desired and/or inner welding
wheel 18 may have a flat or straight or curved or multiple curved
surfaces. Inner welding wheel 18 in this embodiment may be mounted
with bearings on support 90.
[0053] FIG. 5 is an end view of FIG. 4 along lines 5-5 with some
additional structures provided. In this example, support arm 80 may
be rotatable around hinge 82 to thereby raise and/or lower outer
wheel 12 for engagement with the outer surface of the filter
material strips to be welded together.
[0054] FIG. 6 shows a possible plan view of the mounting for outer
wheel 12. It will be noticed in the drawing of FIG. 6 that the
outline of inner wheel 18 is superimposed such that straight
conical surfaces 60 are seen and inner wheel 18 is otherwise
aligned with outer wheel 12. If desired, arm 80 may be adjustable
to move outer wheel closer to or away from mandrel 16. The relative
angle of mandrel 16 and outer wheel may be adjusted as desired to
track the seam for welding the strips of filter material
together.
[0055] In one possible electrical configuration for the embodiment
of tubular filter material construction machine 10C, inner wheel 18
acts to short together the two disks 86 and 88 which form outer
welding wheel 12. Because inner welding wheel 18 is not
electrically driven in this possible embodiment, there is no need
to connect a cable to welding wheel 18 inside mandrel 16 for
electrical welding current. For this electrical configuration,
resistance-welding may be accomplished by maintaining the two
insulated disks 86 and 88 on the outside of mandrel 16 at different
electrical potentials whereby surface 60 of inner roller or welding
wheel 18 acts as a shorting bridge. In this case, current-flow is
from a first of the disks 86 and 88 through the mesh layers to
relatively flat surface 60 of inner welding wheel 18 in mandrel 16
and back through the mesh to the second disk. In this way, two
continuously welded spiral seams may be formed. However, it may be
more desirable to utilize this configuration when fewer filter
material layers are utilized, for instance, depending on the mesh,
when less than two filter material layers form the mesh tubular
screen to be created.
[0056] In another electrical configuration, current-flow may be
directed to both disks 86 and 88 of outer welding wheel 12 to inner
welding wheel 18 inside mandrel. Again, two current paths are
formed which may produce two continuous welded seams. In this
embodiment, at the end of the shaft of inner welding wheel 18, a
sliding rotary contact such as rotary contact 58 shown in FIG. 3 or
rotary contact 70 shown in FIG. 1.
[0057] In one possible embodiment, a cooling system (not shown) may
be utilized for cooling the assembly of inner welding wheel 18.
Either air cooling or fluid cooling such as water may be utilized.
Such cooling will also help to avoid loss of hardness of the
welding bronze. For instance, water may be directed or pumped
through tubulars to a cooling tank, spray, rotary connections, or
the like, for inner welding wheel 18.
[0058] The resulting woven mesh or filter material tubular screen
90 may have any desired length L as indicated in FIG. 8. Tubular
screen 90 may be cut off to the desired length as it comes off of
the woven mesh tubular construction machine discussed hereinbefore.
The resulting spiral wound tubular 90 is free standing without the
need for internal supports. Thus, if made of spirally welded woven
mesh, tubular screen 90 may be inspected by passing inspection
lighting through the interior of the woven tubular mesh to verify
quality construction. Tubular screen 90 may be used in new
applications suitable only for free-standing tubular screens of any
length so as to permit quality inspections and/or to reduce the
costs associated with prior art tubular filter material screens.
The resulting woven mesh tubular screen 90 may also be used in
place of more expensive tubular screens which are made by the
laborious prior art methods such as those made with longitudinal
seams as discussed hereinbefore. Moreover, tubular screen 90 may be
quite long so as to replace multiple tubular screens that were
welded together endwise in the prior art to thereby provide a
better filter continuous screen at a lower cost.
[0059] As an example of use, tubular 90 may be used with downhole
sand control filter 98 of any length shown very generally in FIG.
9. For instance, tubular screen 90 may, if desired, be positioned
inside of perforated tubular 92 by sliding a desired length of
continuously formed tubular screen 90 therein. Tubular screen 90 is
then held in position within sand control filter 98 with end caps
94 and 96 which may be adapted to connection to pipe strings or the
like for lowering into well bores. In this case, the maximum outer
diameter of tubular screen 90 and perforated tubular 92 is limited
to that of the wellbore through which it must be passed prior to
being positioned at the zone of interest, generally less than about
18 inches and often smaller diameter but of any desired length. If
desired, tubular screen 90 may also be slid onto perforated
interior tubulars such as perforated tubing, drill pipe, or the
like, after being inspected to very quality. For downhole sand
control purposes, it is normally desirable to utilize a continuous
spiral weld in tubular 90 to avoid leakage between discontinuities
of the spiral weld. Spiral wrapped screen 90 can be made at one
location and shipped to any location for quality inspections and/or
for combining with perforated tubular 92, which may be made
elsewhere. Alternatively, the tubular filter construction machine
10 can be brought to a desired location so that sand control filter
screen 98 is built at the desired location.
[0060] Downhole sand control filter 98 may, if desired, be used
without an interior perforated screen in contrast to some prior art
devices discussed herein before which have additional blocked
regions. The resulting downhole sand control filter 98 has
maximized open areas to provide for maximum flow. Offsetting
material or wire may be utilized between perforated tubular 92 and
tubular 90 if desire.
[0061] Filter material tubular screen 90 may also be utilized for
other filtering purposes including for filtering screens used in
surface filtering systems which may comprise multiple replaceable
cartridges. Sections of tubular screen 90 may also provide low cost
sifting tubes. The woven mesh tubular screen 90 may comprise
numerous variations. Various types of screens may be utilized,
e.g., the screen openings may vary from one-half inch to three
microns.
[0062] In another embodiment, spiral wrapped tubular screen 90 may
be used in an extruder as a molten plastic extruder screen. In
accord with the present invention, spiral wrapped wire mesh tubular
extruder screens can be built much faster and more cheaply that
presently existing molten plastic extruder screens.
[0063] In another embodiment, filter material tubular 90 may
comprise spiral wound continuous or non-continuously welded filter
cores made using wire mesh or plastic mesh and cut off to length.
Thus, for instance, filter material tubular 90 may be utilized as
low cost car filter cores or other engine filter cores. In another
embodiment, tubular filter material screen 90 may be utilized as a
cylindrical vibrating screen. In another embodiment, tubular filter
material screen 90 may be utilized as sound absorbers, extruder
screens, filter membranes, and general purpose wire mesh tubes.
[0064] The present invention may utilize various types of filter
materials or combinations thereof and may comprise but is not
limited to meshes such as hexagon mesh, metal fiber, plastic woven
mesh, extruded mesh, weldable plastic fibers and other filter
materials are commonly used in various filter screening
applications. The filter material construction screen may utilize
sheets of filter materials such as perforated or punched plastic or
metal sheets. Although filter material may comprise woven filter
material, plastic meshes, or the like, a non-limiting listing of
examples of some of the various types of woven wire or mesh screens
for use in accord with the present invention may be found in one or
more previous patent applications such as U.S. patent application
Ser. No. 10/157,537, entitled Filtering Screen Construction and
Methods, filed May 29, 2002, which is incorporated herein by
reference.
[0065] As well, many variations of a tubular filter material
construction machine 10 are available. A preferred embodiment of
tubular filter material construction machine 10 utilizes an
electro-resistance weld which may be continuous or non-continuous.
Various types of bonding devices and techniques and types of filter
materials such as steel, wire mesh, plastics, papers, or the like,
may also be utilized which may incorporate one or more constituents
or types of bonding such as glue, bonding, ultrasonic welding, heat
welding, and the like. Bonding devices could be implemented in
place of or in conjunction with of the inner and outer welding
wheels through slot 14 in mandrel 16 and preferably arranged for
contacts on the inner sides and outer sides of the filter material.
The tubular filter construction machine may also provide tack welds
if desired. While a single slot or opening 14 is shown, it would be
possible to provide a plurality of slots or openings in mandrel 16.
Moreover a plurality of inner welding electrodes such as inner
welding wheels could be utilized with the plurality of slots or
openings. As noted above the slots or openings need not have a
particular shape. Mandrel 16 may be comprised of steel, insulative
materials and/or friction reducing materials, e.g. TEFLON, in whole
or in sections or portions. In another possible embodiment, mandrel
16 or portions thereof may be moved or rotated with or without
relative rotation of the filter material or portions thereof
positioned on the mandrel. In another possible embodiment, one or
more inner welding wheels 18 may be replaced one or more electrode
plugs, rings, or rotating rings, formed on the outer surface of the
mandrel which are insulated with respect to the remainder of the
mandrel and which may also be water cooled. In another possible
embodiment, mandrel 16 may be rectangular or square shaped or
octagonal or shaped other than as a cylinder. The welding patterns
may be continuous or discontinuous, with special patterns or
arbitrary.
[0066] Accordingly, the foregoing disclosure and description of the
invention is illustrative and explanatory thereof, and it will be
appreciated by those skilled in the art, that various changes in
the ordering of steps, ranges, and/or attributes and parameters, as
well as in the details of the illustrations or combinations of
features of the methods and apparatus discussed herein, may be made
without departing from the spirit of the invention.
* * * * *